Name the chemical constituent of the brown ring ‘Y’. 2. Which of the two solutions – iron (II) sulphate or cone,

Question

Answer the following questions pertaining to the brown ring test for nitric acid:

1. Name the chemical constituent of the brown ring ‘Y’. 

2. Which of the two solutions – iron (II) sulphate or cone, sulphuric acid, do ‘X’ and ‘Z’ represent

3. State why the unstable brown ring decomposes completely on disturbing.

4. Give a reason why the brown ring does not settle down at the bottom of the test tube.

5. Name the gas evolved when acidified iron (II) sulphate reacts with dilute nitric acid in the brown ring test. 

Answer 1

(1) FeSO₄ .NO

(2) X-FeSO₄       Z-H₂SO₄

(3) When test tube is disturbed, cone. H₂SO₄ mixes with water (in Fe₂SO₄ solution). Dilution of cone. H₂SO₄ with water is an exothermic process. The heat so produced assists in the decomposition of unstable brown ring.

(4)Cone. H₂SO₄ ), (density 1.98) is twice as heavy as water (density : 1). As such cone. H₂SO₄ settles down and iron(II) sulphate layer remains alone it resulting in the formation of brown ring at the junction.

(5) Nitric oxide (NO).